实验6 模板类、文件I/O和异常处理

task 4

代码：

Vector.hpp

 1 #pragma once
 2 #include <iostream>
 3 
 4 using namespace std;
 5 
 6 template < typename T>
 7 class Vector {
 8 public:
 9     Vector(int n);
10     Vector(int n, T value);
11     Vector(const Vector<T>& vi);
12     ~Vector();
13 
14     int get_size() const;
15     T& at(int index) const;
16     T& operator[](int index) const;
17 
18     template<typename T>
19     friend void output(const Vector<T>& vi);
20 
21 private:
22     int size;
23     T* ptr;
24 };
25 
26 template<typename T>
27 Vector<T>::Vector(int n) {
28     if (n < 0)
29         throw length_error("Vector<T>::Vector(int)大小为负数");
30 
31     ptr = new T[n];
32     size = n;
33 }
34 
35 template<typename T>
36 Vector<T>::Vector(int n, T value) {
37     if (n < 0)
38         throw length_error("Vector<T>::Vector(int, T)大小为负数");
39 
40     ptr = new T[n];
41     size = n;
42     for (auto i = 0; i < n; i++) {
43         ptr[i] = value;
44     }
45 }
46 
47 template<typename T>
48 Vector<T>::Vector(const Vector<T>& vi) {
49     ptr = new T[vi.get_size()];
50 
51     for (auto i = 0; i < vi.get_size(); i++) {
52         ptr[i] = vi[i];
53     }
54 
55     size = vi.get_size();
56 }
57 
58 template<typename T>
59 Vector<T>::~Vector() {
60     delete[] ptr;
61 }
62 
63 template<typename T>
64 int Vector<T>::get_size() const {
65     return size;
66 }
67 
68 template<typename T>
69 T& Vector<T>::at(int index) const {
70     if (index < 0 || index >= size)
71         throw out_of_range("Vector<T>::at()下标越界");
72 
73     return ptr[index];
74 }
75 
76 template<typename T>
77 T& Vector<T>::operator[](int index) const {
78     if (index < 0 || index >= size)
79         throw out_of_range("Vector<T>::operator[]()下标越界");
80     return ptr[index];
81 }
82 
83 template<typename T>
84 void output(const Vector<T>& vi) {
85     for (int i = 0; i < vi.get_size(); i++) {
86         cout << vi.at(i) << " ";
87     }
88     cout << "\b \n";
89 }

task4.cpp

 1 #include <iostream>
 2 #include "Vector.hpp"
 3 
 4 void test1() {
 5     using namespace std;
 6 
 7     int n;
 8     cout << "Enter n: ";
 9     cin >> n;
10     
11     Vector<double> x1(n);
12     for(auto i = 0; i < n; ++i)
13         x1.at(i) = i * 0.7;
14 
15     cout << "x1: "; output(x1);
16 
17     Vector<int> x2(n, 42);
18     const Vector<int> x3(x2);
19 
20     cout << "x2: "; output(x2);
21     cout << "x3: "; output(x3);
22 
23     x2.at(0) = 77;
24     x2.at(1) = 777;
25     cout << "x2: "; output(x2);
26     cout << "x3: "; output(x3);
27 }
28 
29 void test2() {
30     using namespace std;
31 
32     int n, index;
33     while(cout << "Enter n and index: ", cin >> n >> index) {
34         try {
35             Vector<int> v(n, n);
36             v.at(index) = -999;
37             cout << "v: "; output(v);
38         }
39         catch (const exception &e) {
40             cout << e.what() << endl;
41         }
42     }
43 }
44 
45 int main() {
46     cout << "测试1: 模板类接口测试\n";
47     test1();
48 
49     cout << "\n测试2: 模板类异常处理测试\n";
50     test2();
51 }

运行结果截图：

task 5

代码：

task5.cpp

 1 #include <iostream>
 2 #include <vector>
 3 #include <fstream>
 4 #include <string>
 5 #include <algorithm>
 6 #include <iomanip>
 7 
 8 using namespace std;
 9 
10 class Stu {
11 public:
12     int get_score() const { return score; }
13     string get_major() const { return major; }
14 
15     friend istream& operator>>(istream& in, Stu& s);
16     friend ostream& operator<<(ostream& out, const Stu& s);
17 
18 private:
19     string id;
20     string name;
21     string major;
22     int score;
23 };
24 
25 istream& operator>>(istream& in, Stu& s) {
26     in >> s.id >> s.name >> s.major >> s.score;
27 
28     return in;
29 }
30 
31 ostream& operator<<(ostream& out, const Stu& s) {
32     out << setiosflags(ios_base::left);
33     out << setw(15) << s.id
34         << setw(15) << s.name
35         << setw(15) << s.major
36         << setw(15) << s.score;
37 
38     return out;
39 }
40 
41 bool compare_by_solutionInfo(const Stu& s1, const Stu& s2) {
42     if (s1.get_major() < s2.get_major())
43         return true;
44 
45     if (s1.get_major() == s2.get_major())
46         return s1.get_score() > s2.get_score();
47 
48     return false;
49 }
50 
51 void output(ostream& out, const vector<Stu> &s) {
52     for (auto &i : s) {
53         out << i << endl;
54     }
55 }
56 
57 void save(const string& filename, vector<Stu> &s) {
58     ofstream out(filename);
59     if (!out.is_open()) {
60         cout << "fail to open file to write\n";
61         return;
62     }
63 
64     output(out, s);
65     out.close();
66 }
67 
68 void load(const string& filename, vector<Stu> &s) {
69     ifstream in(filename);
70     if (!in.is_open()) {
71         cout << "fail to open file to read\n";
72         return;
73     }
74 
75     string title_line;
76     getline(in, title_line);
77 
78     Stu t;
79     while (in >> t) {
80         s.push_back(t);
81     }
82 
83     in.close();
84 }
85 
86 int main() {
87     vector<Stu> s;
88 
89     load("data5.txt", s);
90     sort(s.begin(), s.end(), compare_by_solutionInfo);
91     output(cout, s);
92     save("ans.txt", s);
93 
94 }

运行结果截图：